1. Field of the Invention
The present invention relates to a folding bicycle.
2. Description of the Related Art
A folding bicycle has to be moved sometimes after it is folded. Several techniques of combining small wheels and a folding bicycle have been disclosed to facilitate moving the folding bicycle after it is folded. For example, U.S. Pat. No. 7,591,473 discloses a folding bicycle. The rear seat frame of the folding bicycle has four small wheels. When the bicycle is in a usage state, the small wheels are on the rear seat frame (above the rear wheel). When a user wants to fold the bicycle, he or she rotates the rear wheel through 180 degrees around a hinge axle such that the small wheels contact the ground. This motion folds the rear wheel and makes the small wheels contact the ground so that the folded bicycle can be moved with the small wheels. However, when the user wants to pull the folded bicycle, he or she has to bend down, which makes him or her uncomfortable. Also, due to the design of the rolling direction of the small wheels, the folded bicycle tends to tip to the left or right. Thus the user has to balance the folded bicycle with more wrist force when pulling the folded bicycle. This may hurt the user's wrists.
In addition, U.S. Pat. No. 7,341,270 discloses a carrier rack of a folding bicycle equipped with two small wheels. When it is desired to use the small wheels, a user has to collapse the carrier rack and then turn the carrier rack toward the ground such that the small wheels contact the ground. The design of the carrier rack is complicated, and the height of the carrier rack is too great and is not the best design of a carrier rack. Moreover, the user also has to bend down to pull the folded bicycle, which is uncomfortable. Furthermore, because the two small wheels are located above the rear wheel when the bicycle is unfolded and below the rear wheel when the bicycle is folded, the width is too great to allow the bicycle to be moved conveniently (e.g., when passing through the entrance of public transportation station or the door of a train).
Therefore, it is desirable to provide a folding bicycle which can be easily drawn, preferably like a luggage case. Such a folding bicycle allows a user to draw it in a comfortable way and will not tilt easily when being drawn. Also, the width of such a folding bicycle should not be too great when the folding bicycle is drawn.